This article about industrial test №1.Replacement the 28x28mm cast iron cylpebs (surface hardness 44-47HRC) to the 40mm steel grinding balls with the fourth hardness group (surface hardness no less 61HRC). It should be noted, our client specializes in the aerated concrete blocks production.
The first mill commission inspection was in early February 2018.
Method without unloading grinding balls from the mill had used for grinding media average size determination in the test mill. We have made the geometrical dimensions measurements of the selected samples; we have determined the grinding media maximum and minimum dimensions. We have found the grinding balls average size is 37 mm in the mill. The cylpebs size varies from 15mm to 18mm in the mill. The steel grinding balls loading quantity was the same as the previously loaded cylpebs quantity (approximately 1 ton per day, with the continuously mill operation). 15 tons of the 40 mm steel grinding balls have been loaded into the mill since industrial test start. 15 tons — 43% of the mill load norm by grinding media. The 35 tons of grinding media is total mill loads. The mill electricity data consumption show the grinding media weight in mill has been above the norm. In this regard, the technologist has decided to reduce the daily loading rate by 10%.
The mill’s productivity remains within the planned schedule. It should be noted, there was the grinding media composition change in mill, because the cast iron cylpebs are softer than steel grinding balls (the hardness difference is 15-20HRC). I.e. accelerated wear the cast iron cylpebs by the steel balls led to form an environment inside the mill with larger grinding media average diameter than before. The grinding media diameter from 18mm to 32mm has dropped out in grinding media mixture due to the large hardness difference between steel grinding balls and cast iron cylpebs. This resulted in a slight deterioration quality the grinding material, the grinding became coarser — the share of a large class in the grinding material increased at the mill discharge. This is a normal temporary phenomenon occurs in all tests with the replacement the softer grinding media for more solid.
It was decided to load the test mill with 30 mm steel grinding balls after mill inspection and results analysis the crushed material sieving. This will short the formation period a necessary grinding composition of the grinding balls in the mill and will achieve the desired grinding fineness. We draw your attention, the 30 mm and 40 mm steel grinding balls have identical hardness values and steel chemical composition, extremely important for the grinding media formation in the mill.
The next mill inspection scheduled for early April, when the cylpebs should completely exit from the mill and the grinding media will consist exclusively of steel balls. The necessary grinding composition of the grinding balls in the mill must be formed by this time and the technological grinding parameters will meet to client requirements.
We hope this industrial test will be interest to our readers and you will follow its progress in our articles.